Up to now, any parenteral alimentation solution which contains a reducing sugar as well as essential and non-essential amino acids and which further contains electrolytes essential for the living body such as sodium, potassium, phosphorus, magnesium, chlorine and the like has not been put to practical use. For example, although an amino acid infusion solution containing electrolytes has been known, no reducing sugar is contained therein and, in an infusion solution containing both amino acids and a reducing sugar, only sodium and chlorine are present as electrolytes [IYAKUHIN KENKYU, 12, (1), 91-111 (1981)]. In addition, these sodium and chlorine are not intentionally added to an infusion solution but they are inevitably derived from an amino acid component used. For example, when an amino acid is used in the form of its hydrochloride, chlorine is derived therefrom and, when an amino acid hydrochloride is neutralized, sodium is derived therefrom.
In addition to difficulty of determination of an optimum composition, a parenteral alimentation solution containing a reducing sugar, amino acids and electrolytes which are essential nutrients has not been hitherto put to practical use because it is not possible to overcome such a technical difficulty that the alimentation solution turns brown (so-called, browning) due to Maillard reaction of a reducing sugar, for example, glucose with an amino acid during heat sterilization or storage and that browing due to the amino acid and glucose is accelerated and increased in the presence of electrolytes [The Journal of Nutrition, 112, 1631-1637 (1982)]. Thus, in order to prevent such browning, it has been proposed to reduce amounts of electrolytes and further to use L-tryptophan and L-proline which are said to be mainly responsible for browning [The Journal of Nutrition, 112, 1634 (1982)] in their N-acylated forms [Japanese Patent Laid Open Publication No. 115909/1976; and Shinyaku to Rinsho, 29, 305 (1980)].
However, even if it is possible to prevent browning of an infusion solution by using L-proline and L-tryptophan in their N-acylated forms, it is hard to say that N-acylated forms of L-proline and L-tryptophan are most suitable for the living body because these N-acylated amino acids per se are non-physiological amino acids. In addition, as electrolytes, only sodium and chlorine are contained in the infusion solution prepared according to such a known method, but other electrolytes essential to the living body such as potassium, magnesium, phosphorus, etc. are not contained therein.
Accordingly, up to now, in practice, an electrolyte infusion solution and an amino acid-reducing sugar infusion solution has been admixed just prior to administration or they have been separately administered. However, when admixing these solutions, it is necessary to control the pH and osmotic pressure of the resulting mixture suitable for a patient to be administered because they are different from those of the original solutions as prepared and, in addition, there is a problem that the amounts of sodium and chlorine in the mixture should be calculated so as to avoid administration of excess amounts of sodium and chlorine to a patient, when the solutions contain sodium and chlorine. Further, when the solutions are admixed, the possibility of contamination with various microorganisms is increased. In case of administering both solutions separately and successively, a long infusion time is required, which causes pain to a patient for a long time. Further, there is a problem in that a sufficient nutritional effect cannot be expected because each electrolyte which is necessary for an amino acid metabolism is not infused at the same time of infusion of the amino acid.
Thus, in this field of the art, it has been strongly desired to develop a parenteral alimentation solution in which amino acids per se are used without any modification and a reducing sugar and electrolytes are added, in addition, browning due to Maillard reaction is prevented.